Effects of rice amylose content and processing conditions on the quality of rice and bean-based expanded extrudates

Abstract

Effects of rice amylose content (6.1%, 17.7%, and 23.1%), moisture content of raw formulations (18% and 22%) and the maximum extrusion barrel temperature (100 and 140°C) on physical, sensorial, and nutritional properties of rice and bean‐based expanded extrudates were determined. Extrudates with high expansion ratio, low density, low hardness, and good sensory acceptance were obtained at processing conditions of 18% feed moisture and 140°C barrel temperature using rice flour containing 6.1% amylose. In general, the lowest moisture content of 18% and the highest temperature of 140°C promoted more desirable expansion ratio and crispy extrudates. The extrusion processing temperatures studied did not change the thiamine content present in the raw formulation. Also, extrudates obtained at 18% moisture content and 140°C barrel temperature presented the highest free phenolics content and the lowest insoluble fiber content, which was partially solubilized with the extrusion process at 140°C. Practical applications The composition and the physical characteristics of expanded extrudates depends on several process parameters, such as characteristics of the formulation, extrusion temperature, moisture content of the formulation, and others. The interactions between ingredients used in the formulations of the extrudates and the effects of changes in the raw materials are important not only for technological properties but also for the nutritional and sensory effects of end products. Results of the present study provides support for the quality of rice and bean‐based extrudates as a function of the rice source used in the formulation, indicating adequate moisture content and maximum barrel temperature for achieving high‐quality extrudates.